Liquid composition for degreasing surfaces and process of preparation



Patented Feb. 8, 1938 UNITED STATES LIQUID COMPOSITION FOR DEGREASINGSURFACES AND PROCESS TION F PREPARA- Alton F. Curran, Maiden, Mass,assignor to The Curran Corporation, Maiden, Mass., a corporation ofMassachusetts No Drawing. Application January 11, 1936, Serial No.58,758

9 Claims.

This invention relates to a liquid composition for degreasing andotherwise conditioning surfaces and the process of preparing suchcomposition. While not limited thereto, the composition of the presentirfvention is intended for the purpose of degreasing metal surfaces ofall kinds while at the same time exposing the surface to the action offree caustic alkali in desired amount, depending upon the particularmetal being treated and the particular effect to be produced on themetal surface.

From the standpoint of its stability and physical homogeneity, theliquid composition of the present invention can be considered as asolution of liquid soap and free alkali in an organic solvent which ispreferably greatly diluted with another organic solvent of higheffectiveness as a grease solvent. The stability and physicalhomogeneity of such a composition is attributable 20 to the fact thatother than the very small amount of water of reaction present therein,it is subsantialiy anhydrous. Indeed, when a substantial amount ofadditional water is admixed therewith, say, about 15%, its soap contenttends to 25 separate out, possibly on account of the saltingout effectof the substantial amount of aqueous alkali solution produced therein.

Generally speaking, the composition of the present invention is preparedby dissolving caustic alkali in a suitable organic solv'entin thesubstantial absence of water and adding the re- 1 suiting solution toliquid soap-forming substance in amount calculated to yield liquid soapsolu-' tion containing free alkali. The resulting composition iscompatible or miscible with a large amount of various grease solvents,such as pine oil, kerosene, light fuel oil, and liquid hydrocarbons ingeneral, chlorinated hydrocarbons and the like. While grease solvent mayappear in the composition as sold, it is generally preferable that theuser add most, if not all, of the grease solvent to the compositionpreparatory to its use so as to save the expense-of packaging andshipping the grease solvent, which is avail able virtually everywhereand is readily miscible with the composition.

An important advantage of the composition of the present invention isits ready self-emulsifiability in water. This means that once thecomposition has been applied to a metal or other surface to be degreasedand the grease solvent has been permitted to penetrate the grease andrender it sufficiently fluid to be readily emulsifiable in water, watermay be delivered in copious quan- 55 tity, as from a hose nozzle, ontothe surface so as to wash away the grease in emulsified form togetherwith the composition, the soap content of the composition dissolvinginthe water-and acting as 'the emulsifying agent forthe solventmodifiedgrease and the grease solvent. The

quality of self-emulsifiability of the composition is traceable to itsfree alkali content; for when it is devoid of free alkali, it does notlend itself to being readily or cleanly washed away together with greasysubstance from'the surface to which it is applied. The readyself-emulsifiabilityof the composition may be displayed by pouring aWhile it is possible to use-various alkalies, ineluding caustic soda,for saponi'fying soap-form-- ing substances to produce the liquid orsemiliquid soap component of the compositions of the. present invention,causticpotash is generally preferable for such purpose as ityields'liquid soaps from a wider variety of saponifiable substances, forinstance, inexpensive saponifiable substances such as are mostpracticable for such compositions. Thus, the inexpensive liquidsaponifiable substance known on the market as Tallol yields uponsaponification' with caustic potash a liquid soap of especially highgreaseemulsifying potency probably by reason of the fact that thissaponifiable substance which is available as a by-product from kraftpulp manufacture, is rich in both rosinacids and fatty acids of complexcharacter. I may hence use Tallol as the soap-forming substance andsaponify such substance to form a soap of suitable character withcaustic potash-or with a mixture of caustic potash and caustic sodacontaining up to about 50%by Weight of caustic soda. Other alkalies,such as ammonia, or alkali equivalent or bases, such astriethylanolamine and other amines, may be used in lieu of causticpotash to produce the desired liquid or gell-like soap, but because suchother alkalies or alkali equivalents are more expensive than causticpotash and present no particular advantage thereover for my purpose, Iconsider them less desirable, excepting perhaps in special cases.

The organic-solvent employed to carry the alkali to the saponifiablesubstance may, in some cases, advantageously be a phenol. When substancein amount more than that necessary for stantiallyj anhydrous causticalkali is added to cresylic acid, it dissolves and reactsto form alkalicresylate. Alkaliin excess of that forming the cresylate does not'gointo solution. Accordingly, I' add to the cresylic acid an amount ofcaustic alkali calculated to react withsubstantially all of thecresylic-acid. Alkali cresylate containing combined therewith. alkaliin. amount much greater than that necessary to saponify the liquidsoap-forming substance isthen added to such substance, with the resultthat the alkali radical disassociates itself from" the cresylic and.

radical to combine with the soap-forming substance. Indeed, whenalkalias alkali cresylateis added to the liquid soap-forming substancein.- amount'theoretically necessary to saponify such substance,substantially all of the alkali disassociates itself from the cresylicacid to combine .with the soap-forming substance. By'addingalkaliasalkali cresylate in amount greater than that capable of combining withthe soap-form- .ing substance, the alkali'cresylate provided-in thecomposition tends to hydrolyze and thus to furinduce promptself-emulsifiability of the compo-- sition. To this end, after thesoap-forming substance has been treated with alkali combined ascresylate in'amount calc'ulated to effect substan tially completesaponiflcation of the 'soap-form-' ing substance, ,additionalffreealkali is added in the form of a substantially anhydrous solution insuitable inert organic solvent, preferably ethyl,

"'butyl, or" other alcohol, and in amount greater thanthattheoreticallycapable. of combining with the free cresylic acid originally combinedwith alkali but then transferred tothe soap-forming substance. If"desired, such inert organic liquids as diethylene glycolwmonobutylether, and diacetone, all-"of which are solvents of caustic alkali,might be used in lieu ofalcohol. Insome instances, as when maximumalkalinity in the finished composition is desired from a given alkaliusage beyond that necessary for saponification -of the soap-formingsubstance, the use of cresylic acid asa solvent or carrier for thealkaliis dispensed with and alkali in the form of a substantiallyanhydrous solution in. suitable inert organic solvent is added tothesoap-forming subsaponifying such substance.

It'is, of course,-possible to prepare a wide range of compositionsembodying the present invention from suitable raw materials employed invarious amounts. It is to be understood, therefore, that the particularcompositions and their mode of preparation presently to be described aremerely illustrative. use Tallol as the soap-forming substance. TheTallol' sold'on the market may contain various proportions of rosinacids and fatty acids, but, for my purpose, I regard as mostsatisfactory a grade of Tallol containing about 45% to 70% of rosin'acids, about 45% to 20% of" fatty acids, and about-lO% of inert orunsaponifiableorganic substance probably of the nature of hydrocarbon.Thus, I=may start-with, say, IOO'pa-rts by weight of Tallol'specificallycomposed of 45% rosin acids, 45% fatty acids, and-10% inert'sub- As"already indicated, I prefer to stance. I have determined thatthisspeciflc Tal 101 requires about 16parts by weight of caustic potashfor substantially complete saponiflcation. In saponifying the Tallol, Iadd thereto the substantially anhydrous solution of caustic potash ininert organic solvent or carrier. When the carrier is cresylic acid, 32parts by weight of cresylic acid should be used for carrying ortransferring to the parts by weight of 'Tallol the 16 parts by weight ofcaustic potash required for substantially complete saponification. Ihence admix caustic potash with cresylic acid in such proportions tocause the potash to consume the cresylic acid completely by reaction toform liquid cresylate and simultaneously to go into solution. Theresulting liquid cresylate is then combined with the Tallol, inconsequence of which the potassiumradical disassociates itselfpractically completely from the cresylate to saponify the -'I allol,thereby regenerating the cresylic acid.

When grease solvent is added to the resulting Tallol-soap-containingcomposition, the composition does not emulsify or wash away as easily asdesired from a surface to which it is applied. I have found, however,that when an inert organic liquid solution of free alkali insubstantially anhydrous condition is added'to the composition, it isrendered readily self-emulsifying even when a large amount ofwater-immiscible grease solvent is associated with the composition. Oneway of furnishing the composition with free alkali is to dissolvesubstantially dry caustic'potash in substantially anhydrous, inertorganic liquid miscible with the composition, for instance, ethyl,butyl, or other alcohol. The amount of dissolved free alkali added tothe composition is preferably in excess of that theoreticallycombinablewith the cresylic acid regenerated in the composition. Thus,to the particular composition hereinbefore described, I add more than 16parts by weight of dissolved caustic potash, for instance, as much as 30or even more parts by weight of caustic potash. The caustic potash maybe dissolved completely in, say, 2 to 3 parts of itsweightof ethyl orbutyl alcohol and the resulting alcoholic solution added to thecomposition. The resulting composition containing free caustic alkali iscompatible or miscible with a large amountof grease solvent, such as,kerosene, light fuel oil, pine oil, xylol, trichlorethylene, carbontetrachloride, etc., which may be used to dilute the composition at anytime preparatory to use.

A composition prepared as hereinbefore described is readilyself-emulsifiable; and this property is, as already indicated, exhibitedat once by its break-up upon being added to water into a milky emulsionsubstantially devoid of visible grease solvent particles even whengrease solvent is by far its largest single component. The compositionis an excellent degreasing agency especially for metal surfaces and isuseful for such purposes as degreasing metals preparatory toelectro-plating and cleaning the bores of firearms and cannons. Thegrease solvent component 'of the composition gets at the greasecontamination present on a surface and conditions it for promptemulsiflcation and its free alkali component tends to react with suchsaponiflable ingredient as may be associated with the greasecontamination to form a soluble soap which is dissolved and washed awayalong with the composition and unsaponiflable grease ingredients underthe action of wash water. When metals of the class of iron or steel aretreated with the composition, such metal oxide as may be present on thesurface tends to react with the free alkali content of thecompositionand .to be washed away along with the wash water employed inremoving the composition. The metal surface is thus well-conditioned foran electroplating operationf The free alkali component of thecomposition also tends to etch the metal surface and thus to leave itwith a tooth conducive to good bonding afiinity for metal plating. Whenthe composition is applied to metals of the class of aluminum, whichtend to react with alkali to form an oxide coating, it may be of valuein that its .degreasing action is attended by formation of an oxidecoating. After washing the composition from oxide-coated aluminum, thealuminum is useful for some purposes as such or it may be coated ordyed. Thus, the dyeing of the oxide-coated aluminum surface may beefiected with dyes capable of reacting with the oxide coating togenerate insoluble color lakes.

In lieu of using cresylic acid or other phenol as a carrier forsubstantially anhydrous caustic alkali, an alcoholic or equivalent inertorganic liquid solution of the causticalkali may supply both the alkalinecessary to ,saponify the soapforming substance and the free alkalidesired in the finished composition. Thus, substantially dry causticpotash in excess of 16 parts by weight may be dissolved in theappropriate volume of ethyl, butyl, or other alcohol and the alcoholiccaustic potash solution then admixed with the 100 parts by weight ofTallol hereinbefore described to produce the desired finishedcomposition containing free'alkali. Since the amount of free alkali usedin excess of 16 parts by weight determines the free alkalinity of theresulting composition, this amount is controlled, 1

depending upon the particular use to which the composition is to be put.A composition de-' void of alkali cresylate is preferred for a usewherein maximum free alkalinity is desired, for instance, in formingoxide-coated aluminum. In this connection, it might be noted that whencresylic acid is used as an alkali carrier in the preparation of acomposition, it is necessary in 2 order to impart to the composition theproperty of ready seli-emulsifiability to provide alkali in amountgreater than that necessary for saponifying the [*allol soap andcombining with all of the cresylic acid. It is thus seen that by avoiding the use of cresylic acid, it is possible through the use of a givenamount of alkali to realize finished compositions of maximum freealkalinity.- In those instances, however, when an instantlyself-emulsifying composition having minimum tendency to attack metal isdesired, the provision of alkali as alkali cresylate in the compositionmay be preferable even though alkali must be used in amount beyond thatnecessary to form the soap and cresylate in order to impart to thecomposition the quality of ready self-emulsifiability. Compositions thusprepared with an alkali cresylate content may be closely controlled intheir reactivity on metals. Apparently the alkali cresylate content ofsuch compositions hydrolyzes to liberate free alkali and the hydroxylions thus generated repress the ionization of the free alkali presenttherein beyond that combinable as cresylate. In any event, acresylate-containing composition wherein there is free alkali beyondthat combinable as cresylate has the desired property of readyself-emulsifiability probably on account of its considersolvent tosurfaces, for instance, to metal surfaces to be degreased and/orotherwise conditioned thereby. The compositions thus applied arepreferably anhydrous, excepting for the small amount of water liberatedin the saponification of the soap-forming substance and the small amountof water liberated in the formation of The various compositions of thepresent invention exhibit the property of true solutions in so far asconcerns their substantial physical homogeneity and stability and, infact, when diluted with large amount of grease solvent, suchas'kerosene, are

of clear, sparkling appearance and highly penetrative of greasecontaminations. preciable amount of water is added to such compositions,they become unstable in the respect that soap particlestend to separateout therefrom. However, the small amount of water of reaction present insuch compositions is sufficient to promote reactivity of their freealkali content with metal surfaces when the free alkali content isunrepressed and suflicicntly great to promote such reactivity; and thesmall amount of water of reaction present in such compositions is alsosufficient to promote hydrolysis of the alkali cresylate and thus toensure a sufficient buffer efiect against a small free alkali'contcnt inthe compositions beyond that combinable as cresylate to inhibit anyappreciable attack on metal surfaces.

In lieu'of using Tallol as the liquid soap-forming substance of mycompositions, I may use such other liquid soap-forming substance asliquid fatty acid or an admixture of fatty acid and rosin in suitableproportions. Thus, the'liquid.

When an apalkali cresylate, when the latter compound also .appears inthe composition.

fatty acid may be oleic acid or such other liquid iatty acids as arederived from fish, corn, castor, or similar oils. When liquid fatty acidand rosin are combined or mixed, the proportions employed in the mixturemay be such as to approximate the composition of the Tallol available asa byproduct from kraft pulp manufacture. From the standpoint ofexcellence .or results and low cost, however, it is preferable to employTallol whenever Tallol is available.

In lieu of cresylic acid, such as the ortho, meta, and para cresol,other phenols, such as carbolic acid, xylenol, alpha and beta naphthols,hydrogenated phenol (hexalin), etc. might be used as the alkali solventor carrier in preparing compositions embodying the present invention,but 'cresylic acid is preferable because of its low cost and theeminently satisfactory results realized therewith.

I claim:--

1. A substantially anhydrous, alkaline liquid composition for degreasingand cleaning purpose, said composition being possessed of homogeneityand stability characteristics comparable to those of a true solution andcomprising watersoluble soap, alkali in free, water-soluble conditionand combined as phenolate, and liquid hydrocarbon grease solvent, saidcomposition being substantially devoidof water other than that incidentto the formation of said soap and ,phenolate.

2. A substantially anhydrous, alkaline liquid composition for degreasingand cleaning purpose, said composition being possessed of homogeneityand stability characteristics comparable to those of a true solution andcomprising watersoluble soap, alkali in free, water-soluble condition,and liquid hydrocarbon grease solvent, said composition beingsubstantially devoid of water other than that incident to the formationof said soap.

a 3. A substantially anhydrous, alkaline liquid composition fordegreasing and cleaning purpose, said composition being possessed ofhomogeneity and stability characteristics comparable to those of a truesolution and comprising watersoluble soap, alkali in free, water-soluble-condition, an organic alkali-solvent, and liquid hydrocarbon greasesolvent, said alkali-solvent being miscible with the other ingredientsof said composition and said composition being substantially devoid ofwater other than that incident to the formation of saidsoap.

4. A substantially anhydrous, alkaline liquid composition for degreasingand cleaning purpose, said composition being possessed of homogeneityand stability characteristics comparable to those of atrue solutionandcomprising watersoluble soap, alkali in free, water-soluble condition,an alcohol solvent of said free alkali, and liquid hydrocarbon greasesolvent, said composition being substantially devoid of water other thanthat incident to the formation of said soap.

5. A liquid composition for degreasing and cleaning purpose, saidcomposition being of alkalinecharacter and of homogeneity and stabilitycharacteristics comparable to those of a true solution and comprisingliquid potassium soap, water-soluble alkali in free condition, anorganic alkali-solvent, and liquid hydrocarbon grease solvent, saidalkali solvent being miscible with the other ingredients of saidcomposition and said composition being substantially devoid of waterother than that incident to the formation of said soap and being brokendown from its true solution characteristics upon the addition thereto ofan appreciable amount of water.

6. A liquid composition for degreasing and cleaning purpose, saidcomposition being of alkaline character and of homogeneity and stabilityamazes characteristics comparable to those of a true solution andcomprising liquid potassium soap, water-soluble alkali. in freecondition, an alcohol solvent of said alkali, and liquid hydrocarbongrease solvent, said composition being substantially devoid of waterother than that incident to the formation of said soap and being brokendown from its true solution characteristics upon the addition thereto ofan appreciable amount of water.

'7. A substantially anhydrous, alkaline liquid composition fordegreasing and cleaning purpose, said composition being possessed ofhomogeneity and stability characteristics comparable to those of a truesolution and comprising liquid potassium soap, water-soluble alkali infree condition and combined as cresylate, and liquid hydrocarbon greasesolvent, said composition being of ready self-emulsifiability in waterand being substantially devoid of water other than that incident to theformation of said soap and cresylate.

8.- A process of preparing an alkaline, substantially homogeneous andstable liquid composition for degreasing and otherwise conditioningsurfaces, which comprise admixing with liquid, fatty-acid-containing,soap-forming substance a substantially anhydrous organic liquid solventcontaining dissolved therein water-soluble alkali in a form combinablewith said substance to form water-soluble soap and in amount in excessof that necessary for saponifying said substance; said organic liquidsolvent being miscible with the other ingredients of the resultingcomposition; and diluting the resulting liquid composition with liquidhydrocarbon grease solvent compatible therewith.

9. A process of preparing an alkaline, substantially homogeneous andstable liquid composition for degreasing and otherwise conditioningsurfaces, which comprises admixing with liq uid, fatty-acid-containing,soap-forming substance substantially anhydrous organicliquid solventcontaining dissolved therein caustic potash in amount in excess of thatnecessary for saponifying said substance; said organic liquid solventbeing miscible with the other ingredients of the resulting composition;and diluting the resulting liquid composition with liquid hydrocarbongrease solvent compatible therewith.

ALTON F. CURRAN.

